The wireless charging technology is to supply energy to a device to be charged by a power supply device using inductive coupling without a wire connection between the power supply device and the device to be charged. The wireless charging technology is divided into an electric field coupling type, an electromagnetic induction type, a magnetic resonance type, a radio wave type or the like, according to different implementation principles. A magnetic resonance type wireless charging circuit comprises an energy transmitting apparatus (including a transmitting coil) and an energy receiving apparatus (including a receiving coil), and the transmitting coil and the receiving coil resonate at a particular frequency. In this case, the energy transmitting apparatus and the energy receiving apparatus can exchange energy with each other to achieve wireless charging.
An existing energy transmitting apparatus for magnetic resonance type wireless charging comprises a high frequency oscillation circuit configured to generate a high frequency oscillation signal; a transmitting coil configured to transmit the high frequency oscillation signal; and a power source module configured to supply power to the high frequency oscillation circuit, wherein the high frequency oscillation circuit comprises a switch transistor.
In the process of implementing the present disclosure, the inventor found that the conventional methods at least will incur the following problems.
The performance of the switch transistor in the high frequency oscillation circuit determines a frequency achievable by a transmission signal (i.e., the high frequency oscillation signal). If a switch transistor with good performance is selected for use, a higher frequency can be achieved by the transmission signal, a longer transmission distance of the transmission signal may be achieved, and better effects of wireless charging will be obtained. However, switch transistors with good performance are of high cost, and cannot be easily purchased. Therefore, only switch transistors with low cost and poor performance can be used in general. In this case, the frequency which can be achieved by the transmission signal is low, the transmission distance of the transmission signal is short, and the effects of wireless charging are poor.